… have an XML file which I parse and the total number of records are 1.9 million, the table has parent child relationship… is very slow, it first checks either parent record exists; if so then child record is inserted, otherwise it first inserts parent…
Post: Multi Range Read (MRR) in MySQL 5.6 and MariaDB 5.5
March 21, 2012 By 10 Comments
… made against base table, the number of these point primary key lookups will be depend on the number of rows that match the condition… of the secondary key tuples fetched, then the number of range lookups will be: CEIL(S/N) where, S is the combined size of… columns) involves, reading an index record, and then using the PK column value in the index record to make a lookup in…
Post: Index Condition Pushdown in MySQL 5.6 and MariaDB 5.5 and its performance impact
March 12, 2012 By 12 Comments
… which range condition is applied cannot be used for filtering records. For example, suppose you have a key defined as: KEY…
Post: Percona Live MySQL Conference & Expo Was A Great Event
April 17, 2012 By 2 Comments
… importantly, the mood was strongly optimistic. I think a lot of people arrived with some uncertainty about how it would turn… target audience was there in large numbers and actively engaged. The exhibitors deserve a lot of credit for putting on a great… already. Videos of the keynotes are available on percona.tv for your viewing pleasure anytime. Sheeri Cabral also recorded some of the breakout…
Post: When EXPLAIN estimates can go wrong!
October 13, 2011 By 7 Comments
… average number by the number of intermediate pages.” Obviously this assumption, that all the pages in the requested range have almost similar number of records, fails when the pages between the leftmost and the rightmost page have fewer or larger number of records per page…
Post: Some little known facts about Innodb Insert Buffer
January 13, 2009 By 11 Comments
… be completed. The “inserts” is number of inserts to insert buffer since start and number of merged records is number of records which were merged to their appropriate… least this number of records. For the same reason do not get scared if you see more merged records than inserted. The value of 2246304…
Comment: MySQL File System Fragmentation Benchmarks
September 19, 2008 By 28 Comments
… of $number_of_records/(microtime(1)-$t_temp); do this: $number_of_tables/(microtime(1)-$t_temp); and if you do want to keep it with number_of_record try this ($number_of_records*$number_of_tables)/(microtime…
Post: MVCC: Transaction IDs, Log Sequence numbers and Snapshots
December 19, 2007 By 3 Comments
… Sequence Number (LSN) Log Sequence Numbers correspond to given position in the log files and typically incremented for each log record. Innodb uses number of…, however MVCC is usually implemented without having something like snapshot number. Indeed if you look at it in details visibility for…
Comment: How to Identify Bad Queries in MySQL
January 11, 2011 By 16 Comments
… at the cardinality (number of records) visited compared to the cardinality send. Have 2 million records been checked for sending 3 records to the client? I make an efficiency % of this. (2) Queries that return a lot of records…
Post: The performance effects of new patches
September 9, 2008 By 14 Comments
… accesses to several disks. This patch enables to control the number of the IO threads on Unix/Linux and makes the threads…_buf_flush_burst (default 100) * Burst value These control the number of blocks flushed at once. (flushing: writing modified db pages by…” (For our workload it is better to not store many records in the insert buffer) In conclusion, If you are using…
